(a) Field of the Invention
The present invention relates to a brake system for a motor-driven vehicle, and more particularly to such a brake system which automatically cuts off power supply from the motor-driven vehicle when driven to stop the vehicle from moving.
(b) Description of the Prior Art
The motor of a regular motor-driven vehicle, for example, a motor bicycle, is controlled through power source, which is controlled by a main processing unit and sensor means. As illustrated in FIG. 1, handle grip sensor means, pedal sensor means, vehicle speed sensor means and brake sensor means are respectively connected to a main processing unit, which receives power supply from a battery through a voltage stabilizer circuit, and controls a motor drive to drive the motor subject to detected message from the sensor means connected thereto. The brake sensor means is commonly installed in the hand grip to detect displacement of the brake lever or brake cable. When the brake lever or brake cable is moved over a predetermined distance, the brake sensor means immediately outputs a signal to the main processing unit, causing it to cut off power supply from the motor. This design is not satisfactory in function. Because an elastic fatigue tends to occur after long uses of the brake system, the brake sensor means may be unable to accurately detect the braking operation of the brake system, i.e., the brake sensor means may output an error signal to the main processing unit, causing the main processing unit to keep the motor operating when the rider stops the vehicle, or causing the main processing unit to cut off power supply from the motor when the vehicle is running.